238 Torrey on an Ore of Zinc. 



(c) It now remained to determine the quantity of oxyd of 

 zinc, which was done as follows: — The solution obtained in 

 the preceding experiment, after separating the iron, was 

 precipitated by carbonate of potash. The carbonate of 

 zinc thrown down was tested with ammonia, to be certain of 

 the absence of manganese ; but this alkali dissolved the 

 whole of the precipitate, and proved it to consist of zinc ' 

 alone. On evaporoting the ammonia, and calcining the 

 carbonate, 93.50 grains of oxyd of zinc were obtained. 

 The result of the analysis is : 



Oxyd of zinc, - 93.50 



Oxyd of iron, - 3*60 



Carbon, - - 1-00 



98.00 



Loss, - - 2.00 



1 00.00 



The red oxyd of zinc of New-Jersey, discovered by 

 Bruce, resembles our mineral in composition more than any 

 other ore yet described. It however differs essentially in 

 containing 12 per cent, of manganese, and in the absence of 

 iron. Its external characters are altogether dissimilar. To 

 distinguish it from Bruce's mineral, this may be called ^reen 

 oryj of zinc ; though I am aware that the name is objec- 

 tionable, as there is but one oxyd of zinc, which is white. 



It is much to be regretted that a mineral so interesting 

 and valuable should not be better known. We hope the 

 active search which is making for it will not be without suc- 

 cess. It is by far the richest ore of zinc known ; containing 

 according to Thompson, 75.31 per cent, of metal. The 

 red zinc ore of New-Jersey, beside the manganese which 

 it contains, is always intimately mixed with more than half 

 its weight of Franklinite, from which it is impossible to sep- 

 arate h by mechanical means; while the ore of Ancram is 

 so pure that it can be used without any preparation, either 

 for extracting the metal, or for the manufacture of brass. 



